1 Calculate the work performed in Joules if a cart full of m

1. Calculate the work performed, in Joules, if a cart full of mail and packages is pushed with a force of 65lbs a distance of 15 feet from the mail truck to the sorting table.

Points: 2

2. Calculate the power created (in Watts) if you produced 87.5 Joules of energy over 0.79 seconds while performing a leg extension exercise.

Points: 2

3. The length of the biceps muscle increases 1.7cm over the course of an overhead softball throw. The stiffness constant for the biceps is 225,000 N/cm. Calculate the strain potential energy (in N/m) of the system during the throw.

Points: 4

4. If the gravitational potential energy of the softball thrown overhead is 3.3kg-m²/s², calculate the height above the 5’6” softball player’s head at which the ball was released. A standard softball ball weighs 6 ounces.

Points: 5

5. A crane accidently drops a box full of material into a freshwater pool measuring 20 feet long, 10 feet wide, and 6 feet deep before the box is dropped causing the water level to rise to 6.05 feet after the box is dropped. The box is 10x8x12 inches and the material inside weighs 2.4 lbs/in³. Water weighs 8.3 lbs/gallon. Will the object sink or float?

Solution

1.

the work done is calculated as follows:

W = Fd = [65 lbs ][15 feet]

= 65*[4.4482/1 lb][15][0.3048 m / 1 feet]

= 1321.916 J

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2.

the power created is calculated as follows:

P = W/t = 87.5 J /  0.79 s = 110.76 W

3.

use the below equation and solve the energy.

U = (1/2)kx^2

remaining questions post seperately.